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Recommended Varieties |
Numerous seedling and grafted selections available. It is important to match the orchard site with the right variety. Research is still continuing to select the best varieties for North Is conditions. |
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Climate |
Rain or high humidity during spring to late summer increases the incidence of blight. Some varieties are more susceptible to blight than others. Dry east coast climates are preferred. The leaves and flowers are damaged by unseasonal frosts. Areas subject to frost after mid October may benefit from late leafing varieties. |
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Soil |
Critical. Must be free draining down to 2 metres. Fertile soils of moderately high pH are required. Nutrients need to be well balanced. |
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Markets |
Present local consumption far exceeds local supply and quality NZ kernel is readily sold. Said to one of the few commodity products which has maintained its value over the years. The (heart) timber is amongst the most valuable wood there is, provided it is well grown and trees of large size. Walnut burr is particularly sort after. Heart content varies greatly. |
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Harvesting |
The nuts fall to the ground and must be harvested within a day to avoid deterioration. Various machines (vacuum and hedgehogs) available to pick up nuts. In dry climates, daily collection is less critical. |
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Post-Harvest |
Nuts should be cleaned by water blasting and dried promptly. They will go mouldy if kept damp too long or bagged before internal moisture content is low enough. For home use, air drying on racks is adequate. Assisted drying is required commercially. |
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Orchard layout |
Grafted trees are recommended for smaller orchards or where uniform nut quality is critical. Certain seedling lines come remarkably true to the parent. In humid climates, timber may be the preferred objective. Where timber production is required, initial spacings should be 4 x 5 metres. Half of these should be thinned out in stages. Where nuts only are required, use grafted trees at a maximum of 10 x 10 metres. Having more than one variety will assist with pollination. |
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Orchard Management |
Fertiliser is required. Mowing or spraying under the trees enables easy nut collection. Roots stocks can be J. regia or the hybrid "paradox" for well drained soils. J. nigra is preferred for wetter soils. |
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Pests and diseases |
Apart from blight and root rots in poorly drained soils, other diseases are only of nuisance value. Blight can be controlled with copper sprays. No other compounds are yet registered for use. Puriri moth can cause damage to young trees by ringbarking. Walnuts are palatable to horses and sometimes to possums. |
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Shelter and Irrigation |
Shelter is important, even in mild situations. Wind slows the growth down and cools the microclimate. Irrigation could be useful for very dry areas, especially during establishment. Don’t over water. |
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Payback Period |
Grafted trees can start bearing after a year but an economic crop will not be achieved until at least 8 years under ideal conditions. Cropping is directly related to tree growth (and variety). The slower the growth, the longer the wait for nuts. As seedlings are generally more vigorous, they may be quicker to bear nuts |
Corrections and comments welcomed - Email us
http://www.treecrops.org.nz/knowl/archives/cairnse/walnutable.html
Wednesday, 27 August 2003 - Updated: 2007 August 11